This invention relates to a system and method for identifying vapors and gases, particularly for identifying automotive and commercial refrigerants using infrared spectroscopy; and, which may also include an innovative system for measuring, by direct means, any percentage of air or other contaminant that may be present.
It has been found that certain chlorine-containing fluorocarbons which have commonly been used in refrigerants can damage the ozone layer when released into the atmosphere. This finding has led to the replacement of these damaging fluorocarbons. As the ozone damaging hydrofluorocarbons are removed and new non-damaging fluorocarbons are used, it becomes important to be able to identify and keep segregated the various types of refrigerants. Increased government regulations of the fluorocarbons in the United States adds to the responsibility of the refrigerant service facilities, such as automotive repair facilities, which handle refrigerants.
In the automotive field, chlorine-containing refrigerants known as R12 (CF2Cl2), R22 (CHF2Cl) and various blends have been used as automotive and home air conditioning refrigerants. The tetrafluoroethanes and pentafluoroethane, i.e., R134A (CH2Fxe2x80x94CF3), R134 (CHF2xe2x80x94CHF2), R125 (CHF2CF3) have been found to be non-ozone damaging refrigerants and are presently being recommended and used in automobiles. Older cars may still be using R12 as a refrigerant. Because of the cost involved in converting existing automotive hardware to handle R134A, existing automobile owners may elect to continue using their prior refrigerant. However, because of government regulation, chlorine-containing R12 will no longer be acceptable in new cars. R22, a home air conditioning refrigerant which has been used, as a replacement for R12, because of its lower cost, will also not be acceptable for use as an automobile refrigerant in new automobiles.
It is possible that in an automobile""s refrigerant system, as well as in the storage tanks of auto service centers, that a mixing of the above materials may take place. Because of the dangers associated with certain of the automotive refrigerants, as well as increasing government regulation, it is desirable to identify the individual refrigerant gases in both the automotive systems and storage facilities in order to maintain separate and pure stores of these materials. If a storage tank of refrigerant gases becomes contaminated, it should not be used for refiling an automotive refrigerant system.
In commercial air conditioning/refrigeration installations, there are approximately 25-35 different combinations of commercial refrigerants which are commonly used. As stated previously, certain commercial automotive refrigerants are ozone damaging. In addition, certain commercial refrigerants may damage the elastomeric seals used and may be incompatible with the lubricants used in a system designed for the new commercial refrigerants. Because of the wide variety of refrigerants utilized in the field, it is possible that more than one refrigerant is inadvertently present in a particular commercial refrigeration system and/or refrigerant storage tank. Thus, it is absolutely necessary to be able to identify all materials present in the refrigerant system before it is used commercially.
One method which has been used to identify gases is infrared spectroscopy. Most gases absorb infrared energy at specific wave lengths in the spectrum and, in many cases, at multiple points in the infrared spectrum. Infrared spectroscopy has been used to observe the phenomenon and identify particular gases. Traditional infrared spectroscopy equipment and methods, however, are not practical for field use at installations such as a local automotive repair facility because of cost, size, and their fragility. Existing infrared spectroscopy units, designed for laboratory use, are inappropriate for rigorous xe2x80x9cuncleanxe2x80x9d environments such as that found in a local automotive repair facility. They also fail to meet the requirements of a portable device for transport and operation at a particular commercial establishment having commercial refrigerant systems.
In U.S. Pat. No. 5,610,398, whose disclosure is incorporated herein by reference thereto, a single infrared light source is used to determine the presence of multiple vapor gases in a refrigerant sample. Specifically, the infrared light source illuminates a refrigerant sample which has been placed in a test area (a so-called gas cell). The test area is physically located between the infrared light source and a plurality of infrared detectors. The infrared detectors receive the infrared light after it passes through the refrigerant sample. Each of the infrared detectors is sensitive to a different predetermined wavelength range of infrared light. Each of the infrared detectors is adapted to output a separate electrical signal corresponding to the infrared light received in its respective wavelength range.
Once a refrigerant sample is illuminated by an infrared light source and the plurality of infrared detectors receives infrared light passing through the refrigerant sample, and the resultant electrical signals are amplified and filtered, a processor reads the output electrical signals and determines whether the electrical output signals correspond to a particular refrigerant. The results of this determination are then displayed on an output device. This prior art system is shown in FIG. 1.
Another characteristic of this prior art system lies in the manner in which air is determined in the refrigerant system. Specifically, in U.S. Pat. No. 5,610,398, a multichannel non dispersive infrared sensor is calibrated to measure the amounts of each refrigerant (one per channel) in units of % by volume vs. optical absorbency. When a sample is introduced to the sensor, the optical absorbency of each channel is measured. Using the optical absorbency, the percent by volume is computed by looking into the calibration curves (previously prepared using known sample concentrations). The computed percentages by volume of each channel are then added together, if the total is less than 100%, the balance is called air, even though it could be some other substance. Air is never measured by direct means. The percent by weight is then computed by multiplying the percent by volume of each component by its known molecular weight and re-computing the percent of each component based on their fraction of the total weightxc3x97percentage volume of the sum. Since air is not considered a contaminant, it is left out of the sum when computing the refrigerant percent by weight. The percents by weight of the refrigerants by definition will always add up to 100% even if the air percent by weight is not zero.
It is an object of this invention to provide a method and system for identifying automotive and other commercial refrigerants using infrared spectroscopy that is compact, relatively inexpensive, and more accurate than any in the prior art.